Insulation



Sept. 20, 1949. w 2,482,527

INSULATION Filed June 9, 1944 WITNESSES: 2 INVENTOR @zr/zza hzz 8Y9 a 3 ATTORNEY Patented Sept. 20, 1949 UNITED STATES PATENT OFFICE INSULATION I Application June 9, 1944, Serial No. 539,499

8 Claims.

My invention relates to molded insulation for dynamo-electric machines, and it has particular relation to a preformed molded class B insulator comprising a curved segment of a channel-shaped member adapted to fit (in one or more layers) over a support-ring for the end-turns of the armature-winding of a direct-current machine. Class B insulation is insulation which is able to continuously withstand a temperature of 150 C., or, in general terms, a temperature of more than 125 C. This temperature-limitation ordinarily excludes cellulosic materials or fibrous carbohydrates such as wood-pulp paper, or organicthread cloth, although sometimes a small quantity or layer of such materials may be permitted, in quantities occupying only a small part of the total volume of the insulator.

Because of difiiculties of applying class B insulation to armature-coil support-rings for large direct-current motors and generators, which ma involve rings as large as 100 inches in diameter, it has been standard practice, for a number of years, to place several layers of thin molded strips of class B fibrous insulation, impregnated with a heat-hardeningor thermosetting phenolic resinous binder. These thin strips are held in place by laboriously taping the ring, all around, with several layers of mica, held with glass or asbestos tape. This costly and laborious procedure has been adopted in order to avoid the prohibitively high tool and labor costs, on small quantity orders, for ring-covering channel-members molded to exact size, with thermosetting resins of the phenolic type.

The object of my present invention is to provide a new form of class B insulation for such armature-coil support-rings, utilizing molded, channel-shaped, curved segments, not more than 18 inches long, to fit over various portions of the support-rings. The breaks between successive channebsegments are preferably covered by other channel-segments of appropriately larger size. These channel-segments are molded from class B flexible impregnable insulating material,

and a suitable impregnating binder of a class B hardenable insulating material which will bind the impregnated material into an integral piece which is hard and mechanically rigid, at all portions thereof. The impregnable base-material is preferably asbestos or other inorganic porous material, and the binder is preferably a thermosetting material.

A further object of my invention is to provide a considerable saving in cost, as applied to previous practices for this type of service.

With the foregoing and other objects in view, my invention consists in the systems, combinations, methods, apparatus, structure and parts, hereinafter described and claimed, and illustrated in the accompanying drawing, wherein Fig. 1 is a fragmentary longitudinal sectional View of a direct-current motor, illustrating an application of my invention, Fig. 2 is a fragmentary perspective view of a support-ring, showing the manner of applying my molded segmental insulating channels, and Fig. 3 is a transverse sectional view through one of my molded class B insulatin channels.

I have illustrated my invention in connection with a direct-current motor (which might be a generator), having a stationary field member 4 and a rotatable armature member 5, the latter having a magnetizable core 5, carrying armature windings I. The armature windings l are connected, at one end, to a commutator 8. The endturn portions of the armature windings l are supported, at each end of the armature member 5, on a support-ring 9, which is first covered with insulation It, which constitutes the special detailed object of my invention. My present invention relates more particularly to class B insulation ID, and in general the entire motor or generator will be designed with class B insulation, although my class B support-ring insulation it is also applicable to class A machines.

In accordance with my present invention, the support-ring insulation ID is provided in the form of a plurality of preformed molded insulator-segmerits l2, each of which is a curved segment of a channel-shaped member, having its web portion l3 on the outside, and curved to fit a segment of a circle, as shown in Fig. 2 of the drawing. Each .2 of these segmental channel-members I2 is made an acceptable class B support-ring insulation at in one mechanically rigid, integral piece, composed of a plurality of layers id of molded sheets of initially flexible asbestos paper, which may either be substantially pure asbestos, or commercial forms of asbestos-cloth or asbestos-paper, with or without the addition or admixture of a small percentage of organic fibrous materials, for ease of handling; or, in general, any initially flexible impregnating insulating material may be utilized, which will stand a temperature of more than C. continuously, or which is resistant to attacks of a thermosetting impregnating material which is capable of strongly attacking the usual farms of fibrous carbohydrates.

The layers M are united together, in a hard,

integral whole, by means of an impregnating binder of a harden-able insulating material which will bind the sheets together into an integral piece which is hard and mechanically rigid at all portions thereof. The binder is preferably a thermosetting resin, which is capable of permanently changing its form, as by polymerizing, under the influence of a suitable elevated temperature, applied for a brief time, so as to change its form from a very fluid substance, of the approximate consistency of water, to an extremely hard solid, which does not materially sotten again, even when raised to still higher temperatures than the initial thermose'tting temperature.

The resin may be a copolymer of propylene glycol-maleate and styrene. Other thermosetting resins which might be utilized include the general class of alkyd resins dissolved in a vinyl compound, which include combinations of a polyhydric alcohol, an unsaturated dibasic acid, and '1';

a-v'inyl compound, or, in general, most or all of the resinous reaction-products of organic acids, as well as other hardenable impregnating agents, which could also be utilized. -I prefer, but am not limited to, a resin having an acid value of 50 or more, referring to the number of milligrams of 'KOH necessary to neutralize each gram of the sample.

In the manufacture of my molded segmental channel-members I2, the layers of initially soft or flexible absorbent or irnpregna-ble material, preferably in the form-of sheets, is first laid over a suitable mold 16. Either before or after laying said sheets over the mold they are impregnated with a hardenable insulating binding-material of the class which has already been described. The impregnated sheets are then subjected to heat in a suitable oven, as indicated by dotted lines H, in which the necessary binder-hardening temperature is applied, either with, or without, the application of pressure to the molded article. The resulting product is extremely hard and compact, and it can be made at a relatively small cost, as compared with previous class B insulation for armature-coil support-rings.

Preferably, vas shown in Fig.2,the molded segments 12 aremade in two sizes, the smaller-sized segments being placed directly over the armaturecoil support-ring 9, in abutting relationship, or with slight spaces 18 ,between the abutting ends of the successive segments. These spaces 18 are preferably covered over with a second ring of insulator segments I2 which are of such size as to fit over the first ring of insulator-segments, as clearly shown in Fig. 2.

While I have described my invention in a single preferred form of embodiment, I Wish it to be understood that my-invent'ionis susceptible of changes, without departing from the essential principles thereof. I desire, therefore, thatthe .ppcnded claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A preformed molded insulator comprising a curved segment -of 'a channel-shaped member having its web-portion on the outside and curved to fit a segment-of a circle, less than a complete circle in length, said member being made in one mechanically rigid integral piece composed of an impregnable insulating material which will stand a temperature of more than 125 C. continuously, and an impregnating binder of a hardenable insulating material.

curved segment of a channel-shaped member having its web portion on the outside and curved to fit a segment of a circle, less than a complete circle in length, saidmember being made in one mechanically rigid integral piece composed of an 'impregnable'insulating material which will stand a temperature of more than C. continuously, and an impregnating binder of a thermosetting insulating material.

4. A preformed molded insulator comprising a curved segment of a channel-shaped member having its web portion on the outside and curved to fit a segment of a circle, less than a complete circle in length, said member being made in one mechanically rigid integral piece composed .of asbestos fibers and an impregnating binder :of ;a thermosetting insulating material.

'5. A preformed molded insulator comprising a. curved segment of a channel-shaped member having its web portion on the outside and curved to fita segment of a circle, less than a complete circle in length, said member beingmade fin one mechanically rigid integral piece composed of a plurality of layers of molded sheetsof impregnable insulating material which will stand ea temperature of more than .125 vC. continuously, and an impregnating jbi-nder of :a ihardenable insulating material which will bind said sheets .t0- gether into an integral piece which is hard and mechanically rigid at all portions thereof.

6. The invention as defined in claim 5., characterized by said impregnable layers being of inorganic material 7.. The invention as defined in claim 5, characterized by said impregnable layers being of asbestos.

8. The invention as defined in claim 5., characterized by said binder being a thermosetting material.

CONRAD WEIL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS- .Number .Name Date 491,708 Jeflerson Feb. 14, 1893 932,042 Mattman Aug. 24, 1909 957,290 Wright -May 1-0, 1910 1,150,043 Lamme Aug. 17, 1915 1,190,766 Hubbard July 11, 191.6 1,486,874 Frederick Mai. 18, 1924 1,589,094 Barringer June 15, 1926 1,857,586 Coffee May 10, 1932 1,944,508 Gubler Jan. 23, 1934 2,036,825 Pattman Apr. 7, 1936 2,078,422 Smith Apr. .27, 1937 2,133,183 Baird Oct. 11, 1938 2,319,826 Pellett May 25, 1943 2,363,324 Hill Nov, 21, 1944 2,439,667 'Mathes Apr. 13, 1948 

